SLC25A6 expression level impacts systolic duration and QTc interval duration in zebrafish. (A) Systolic interval normalized to heart period determined from high-speed video recordings of the heart ventricle show reduced systolic duration resulting from SLC25A6 overexpression (SLC25A6 mRNA) compared to controls (Control mRNA). (B) SLC25A6 overexpression did not affect heart rate. Data in (A,B) were compiled from three independent experiments, each encompassing both groups (n = 15). (C) Systolic interval normalized to heart period determined from high-speed video recordings of the heart ventricle show increased systolic duration resulting from approximately 50% knockdown of endogenous slc25a6 mRNA (slc25a6 KD) compared to controls (Control KD). The phenotype was rescued by co-injection of the slc25a6 targeted morpholino with wildtype SLC25A6 mRNA (slc25a6 KD + SLC25A6 mRNA) but not control mRNA (slc25a6 KD + control mRNA). (D) Knockdown of endogenous slc25a6 mRNA did not affect heart rate. Data in (C,D) were compiled from three independent experiments, each encompassing all four groups. n(control KD) = 13, n(slc25a6 KD) = 10, n(slc25a6 KD + control mRNA) = 13, n(slc25a6 KD + SLC25A6 mRNA) = 12. (E) SLC25A6 overexpression (SLC25A6 mRNA) resulted in a decreased QTc interval compared to controls (Control mRNA). (G) 50% downregulation of endogenous slc25a6 mRNA (slc25a6 KD) resulted in an increased QTc interval compared to controls (Control KD). (F,H) SLC25A6 overexpression (SLC25A6 mRNA) and downregulation of endogenous slc25a6 (slc25a6 KD) did not affect heart rate. n = 15 (Control mRNA), n = 15 (SLC25A6 mRNA), n = 14 (Control KD), n = 1 (slc25a6 KD). Corrected QT interval (QTc) was calculated using Bazett’s equation (QTc = QT × √1/RR). Statistical analyses were performed by one-way ANOVA with Tukey’s post-test. *p < 0.05, ***p < 0.001.
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